Retarding evaporation of water



3,459,492 Patented Aug. 5, 1969 United States Patent Office 7 ABSTRACT OF THE DISCLOSURE 31 Claims 1 Y Evaporation of water from reservoirs,-ponds, lakes,

tanks, and the like, is retarded by applying to the surface of the water a thin film formed from l -monoglycerides of saturated, straight chain, fatty acids of 18 to 24 carbon atoms or a mixture of such monoglycerides and long chain primary alkanols.

This invention realtes to ways and means for retarding evaporation of water from bodies thereof. 7

One solution to the problem of retarding'the evaporation of water from reservoirs, ponds, lakes, tanks and other bodies of water is a thin, preferably monomolecular, film of a suitable material on the surface of the body of water. Many materials have been tested for this purpose-and" several have been found to be' effective. Of those materials heretofore tested and found to be etfective only long chain primary alcohols such as n-hexadecanol and n-octadecanol have met the requirements of efficacy, availability, low cost, and non-toxicity relative to plants and animals at useful concentrations. The search for other materials which meet these requirementsv has continued.

This invention is based upon the discovery that normally solid water insoluble l-monoglycerides of saturated, straight chain, C1844 fatty acids, which are generally recognized as safe for human consumption and which are or can be readily available and inexpensive, effectively retard evaporation of water when present in a thin, preferably monomolecular, film at a concentration substantially greater than 10% by weight of said film.

In summary, this invention comprises a. process for retarding the evaporation of water, which comprises forming on the surface of a body of water a thin film consisting essentially of normally solid and water insoluble l-monoglyceri-de material at a concentration substantially greater than about 10% by weight of said film and preferably at least at about 15% by weight of said film. The concepts of this invention include such a film wherein the l-monoglyceride material is at a concentration as great as 100% by weight of the film. However, in preferred embodiments of this invention theifilm also consists essentially of normally solid and water insoluble, primary alkanol material. In these embodiments the concentration of said alkanol material is substantially less than about 90% by weight of the film. Generally, it is in a range from about to 85% by weight of the film. The concentration of said l-monoglyceride material is substantial-1y greater than about 10% by weight of the film and generally it is in a range from about 15 to about 90% by weight of the film.

The normally solid, normally water insoluble, l-monoglyceride material of this invention has a density less than that of water. It consists essentially of at least one l-monogylceride of a saturated, straight chain, C1344 fatty. acids. In preferred embodiments of the invention the l-monoglyceride material consists essentially of a mixture of l-monoglyceride of saturated, straight chain, C1844 fatty acids. Efficacy of l-monoglycerides in retarding evaporation increases rapidly as the chain length of the fatty acid moiety of the monoglyceride molecule increases. If the fatty acid moiety is less than about 18 carbon atoms long, the corresponding l-monoglyceride has little effect on evaporation. However, if the chain is at least 18 carbons long, there is a substantial retardation efi'ect. Examples of l-monoglycerides of this invention include 1-monoglycerides of stearic acid, arachidic acid, behenic acid, lignoceric acid and the like. Especially preferred under the concepts of this invention is l-monoglyceride material containing l-monoglyceri-de of behenic acid at a concentration of at least about 25% by weight of the l-monoglyceride material. Monoglycerides are often accompanied by diglycerides. Diglycerides appear to be ineffective in retarding evaporation and to act as inert diluents of the effective l-monoglycerides. Accordingly, monoglyceride products having monoester contents of at least about by weight, such as those made by the interesterification reaction of glycerol and one or more triglycerides predominating is saturated, straight chain, C fatty acids followed by vacuum distilla tion of the resulting reaction product are preferred sources of l-monoglyceride material under the concepts of this invention.

In those preferred films of the invention wherein the film in addition to l-rnonoglyceride material consists essentially of normally solid, normally water insoluble, C1444 primary akanol material, the n-hexaand n-octadecanols are preferred. An example of such alkanol material is a mixture of n-octadecanol and n-hexadecanol, the weight ratio of the n-octadecanol to the n-hexadecanol being substantially 7:3. In the preferred films of this invention, the long chain primary alkanols help in repairing damage to the mono layer or film and in maintaining it intact while the l-monoglyceride material increases the eflicacy of the film in preventing evaporation and also increases its longevity.

In the practice of the process of this invention the film is formed by adding the film forming material to the body of water at prevailing temperatures, although temperatures at 10-25f C. and higher are preferred. The film forming material can be added by broadcasting it in finely divided condition over the surface of the body of water, by floating chunks of it in the body of water, by pouring or releasing it dissolved in a suitable solvent or dispersed in water, and the like. A suitable solvent is one which is inert, non-toxic, normally volatile and has a density less than the density of water. Examples of a suitable solvent for the film forming material of this in vention include diethyl ether, n-hexane, kerosene, butanol, and the like. In the aqueous dispersion embodiment of this invention, sufiicient water is used in the dispersion to enable the finely divided, solid, film forming material to be dispersed therein. In general a concentration of film forming material in a range from about 1 to about 50% by weight of the dispersion and a water concentration in a range from about 50 to about 99% by weight of the dispersion gives satisfactory results. Preferably the aqueous dispersion should be stable at 2025 C. for substantial lengths of time. To achieve this condition in one preferred embodiment of this invention a suitable dispersing agent is employed. This is material which is inert, non-toxic to animals and plants at use concentrations, compatible with the film forming material, and establishes and maintains in suspension the dispersed particles of film forming material at the concentrations employed in the aqueous dispersion without substantially adversely affecting the evaporation Suppression efficiency of the film forming material upon addition to the body of water. Examples of a suitable dispersing agent include sodium stearate, sodium lauryl sulfate, oxyethylated materials such as polysorbate 80, and the like. The dispersing agent is employed in the aqueous dispersion at a concentration sufiicient to give to the aqueous dispersion the desired degree of dispersion stability, but yet insufiicient to maintain the stability of the dispersion upon addition of the aqueous dispersion to the body of water and substantially adversely affect the evaporation suppression efficiency of the film forming material. A concentration in a range from about 0.1 to about 2% by weight of the film forming material generally gives satisfactory results. Under the concepts of this invention, the aqueous dispersion embodiment is preferred because the film forming material spreads better from the dispersion to form the evaporation retarding film or monolayer on the surface of the body of water.

The quantity of film forming material applied to a body of water depends on the surface area of the body of water to be covered, normally encountered wind velocities and normally encountered temperature and humidity conditions. In general, however, a quantity of film forming material in a range from about 10 to about 300 grams per acre of water surface gives satisfactory results. Where high wind velocities normally prevail this range is on a per day basis.

In addition to the process aspect, this invention also comprises a composition for suppressing water evaporation. This composition consists essentially of a mixture of C1444 primary alkanol material and said l-monoglyceride material. The concentration of said alkanol material is substantially less than about 90% by weight of said mixture and generally it is in a range from about 10 to about 85% by weight of said mixture. The concentration of said l-monoglyceride material is substantially greater than about 10% by weight of said mixture. Generally, it is in a range from about 15 to 90% by weight of said mixture. In one preferred general embodiment of this composition the mixture is dissolved in an inert, non-toxic solvent therefor, a description and examples of which have already been given herein. In another preferred general embodiment of this composition the mixture is dispersed in I water, preferably with the aid of a suitable dispersing agent, a description, concentration and examples of which have already been given herein. These compositions are made by admixing the components thereof at 2025 (3., although higher and lower temperatures can be employed.

This invention is further illustrated by the following Working examples including examples of specific embodiments of the process and composition of this invention. This invention is not limited to these specific embodiments unless otherwise indicated.

Example 1 This example illustrates the practice of a specific embodiment of the process of this invention.

A l-monoglyceride product having a monoester content of at least about 90% by weight of the product and consisting essentially of l-monoglycerides having the fatty acid moieties of distilled, substantially fully hydrogenated, rapeseed oil at the relative weight ratio of said moieties in said oil (l-monoglycerides of behenic acid, arachidic acid and stearic acid at a weight ratio, for example, of about 53:21:26) is dissolved in n-hexane at a concentration of 0.0004 gram per milliliter of solvent.

The resulting solution is poured into a body of water to be covered, the quantity of solution being approximately one liter per 76 square meters of water surface area. The result is a monomolecular film covering the surface of the body of water.

Typical results obtained in the practice of this process are illustrated by the following, tabulated test data obtained in the laboratory. In obtaining these data, the test material was dissolved in n-hexane at a concentration of 0.0004 gram per milliliter of hexane and one milliliterof the solution was added in each case to the surface (area=76 square centimeters) of approximately 200 grams of water in a circular glass dish (3% inches internal diameter and 2 inches deep). The etfect of these test materials in suppressing water evaporation was then determined by storing the dishes in an isolated, but ventilated room at 20-25 C. and weighing them after 48 hours and again, (except in the case of Sample No. 3 identified in the following table), after hours. The loss in grams of water in the dishes in each case was compared against the loss in grams of water in a dish to which no test material had been added. The test results are summarized in the following table.

Percent reduction in evaporation compared Example 1 with the weight ratio of the l-monoglycerides of behenic acid, of araehidie acid and of stearic acid being about 53:21:26.

These data show that l-monoglyceride material of saturated, straight chain C fatty acids substantially retard water evaporation. Moreover, these data show the film forming material of Example 1 to be superior to C1444 primary alkanol material in suppressing evaporation under the conditions involved in the test procedure.

Example 2 This example illustrates the practice of another specific embodiment of the process of this invention, and also illustrates a specific embodiment of a composition of this invention.

Quantities of the l-monoglyceride product described in Example 1, n-octadecanol and n-hexadecanol are dissolved in diethyl ether at a ratio substantially equivalent to two grams of l-monoglyceride material to one gram of n-octadecanol to one gram of n-hexadecanol to one liter of diethyl ether.

The resulting solution is poured into a body of water to be covered, a suitable quantity of the solution per surface area of Water being approximately one liter per 76 square meters of surface area. The result is a monomolecular film covering the surface of the body of water.

Typical results obtained in the practice of this embodiment can be seen from the following tabulated data obtained in the laboratory.

These data were obtained by dissolving the test material in diethyl ether, the ratio in each case being equivalent to four grams of test material to one liter of diethyl ether. One milliliter of the resulting solution in each case was applied to the surface (area=76 square centimeters) of approximately 200 grams of water in dishes like those described in Example 1. The dishes, which included a control sample to which no test material was added, were then placed in an isolated, ventilated room at 2025 C.

first, fifth, eleventh and eighteenth days. The results'are summarized in the following table.

Percent reduction in evaporation compared to control sample Spreading Sample quality of On eleventh n eighteenth For eighteen No. Test material test material On first day On fifth day day day days 1 n-Hexadecanol and n-octa- Good 43. 0 33. 23. 5 29. 5

ge7canol at weight ratio of 2 Test material or Ex. 3 Excellent 32.0 35.1 33.0 20.0 35.0 Test material of Ex. 4 Very good 34. 5 32. 5 36. 5 34. 5 37. 5 Test material of Ex. 5 Poor 44. 0 44.0 40.0 49. 0 45. 5 Test material of Ex. 6 Very poor 32.0 25. 0 10.0 13. 0 19. 8 Test material of Ex. 7 Very poor 33.0 24. 0 36. 5 34. 0 31. 5 7 Test material of Ex. 8 Poor 70. 5 58. 5 42. G 28. 5 52.0

, These data show that l-monoglycerides of saturated, Percent reduction in evaporatuon compared to controlsample straight chain C fatty acids, instead of being detri- Sam-p18 After After Aim mental to the protective action of films containing long Test material tm-ee days six days ten days chain, prlmary alkanol material, actually lmproved evap- 1 mfiexadecanoland 37. 0 27. 0 20 oratlon suppression and lnereased the longevlt y of the octadecanolat weight effect. These data show that 1n general the substltution of ratio of 3:7. o 2 mm forming material 470 530 50 mixed lmono lycerides of saturated stralght chaln C 1 Example and C2042 of fatty aclds for a th1rd of the prlmary alkanol 25 material markedly improves spreading qualities as well The tabulated data demonstrate that the film forming composition of Example 2 is substantially more effective than the primary alkanol material alone in suppressing evaporation under the test conditions.

Examples 3-8 These examples illustrate the practice of other specific embodiments of the process of this invention, and also illustrate other specific compositions of this invention.

The formulations of the evaporation retardant compositions or film forming compositions of these examples are as follows:

Concentration in parts by weight Ex. Ex. Ex. Ex. Ex. Ex. Material 3 4 5 6 7 The compositions of each of these formulations are made in each case by melting together the solid materials, admixing therewith the indicated quantity of water at substantially 100 C. and then stirring the resulting mixture with a high speedstirrer while cooling the same to 50 C. The result in each case is an aqueous dispersion.

In each case the composition is applied to the surface of a body of water at a ratio of 184 grams of dispersion per 76 square meters of surface area.

Typical results obtained in following the practice of the specific embodiments are illustrated by the following comparative data obtained in actual laboratory tests. In each case the test material is made by melting together the components, admixing 10 parts by weight of the molten test material with 90 parts by weight of water at substantially 100 C., stirring the resulting mixturewith a high speed stirred while cooling to 50 C. A quantity of the resulting dispersion in each case was then applied to the surface (area-=76 square centimeters) of 200 grams of water in a dish such as described in Example 1, the quantity in each case being selected to provide 1.65 milligrams of test material in the dish. The dishes were observed for spreading quality of the test material and then, along with a dish containing 200 grams without any test material, which was the control sample, they were placed in an isolated venti- .lated room at 2025' C. The dishes were weighed on the as longevity of the evaporation suppression effect. These data show that the spreading quality of l-monoglyceride material per se is poor. One the other hand, these data show that l-monoglyceride material in which 90% by weight of the l-monoglycerides are l-monoglycerides of C2042 fatty acids gave the best, overall, water evaporation suppression, whether alone or mixed with n-hexadecanol and n-octadecanol.

Example 9 This example illustrates a preferred specific embodiment of the composition of this invention.

The formulation of this specific embodiment is as follows:

Components: Parts by weight l-monoglyceride product from distilled, hydrogenated, rapeseed oil 14 n-Hexadecanol 5.6

Sodium stearate 0.4

Water The l-monoglyceride product from distilled, hydrogenated, rapeseed oil is similar to the l-monoglyceride product described in Example 1.

The composition of this embodiment is made by admixing the l-monoglyceride material, the n-hexadecanol and sodium stearate, and then melting the resulting mixture. The molten mixture is added to the water at 80- C. while stirring with a high shear stirrer. While maintaining vigorous stirring the resulting aqueous dispersion is cooled to 2025 C. During the cooling some foam may form due to the incorporation of air into the dispersion. The foam is eliminated by degassing .the dispersion at 20-25" C. using vacuum. The degassed dispersion is stable and pourable. It is used by adding it to a body of water to be covered, the quantity added being equivalent to 2-4 grams per 76 square meters of surface area. The result is a thin film which substantially retards evaporation.

A sample of the aqueous dispersion according to this formulation was made according to the described procedure. The l-monoglyceride material had a weight percentage of behenic acid moiety and arachidic acid moiety of about 50.5 and 12.3. In carrying out the tests, 0.2, 0.3 and 0.4 milligram portions of the sample were added to the surfaces of water in corresponding dishes described in Example 1. The quantity of water in each dish was 200 grams and the surface area in each case was 76 square centimeters. These dishes plus another dish con- I taining the samequantity of water without any material 7 in it or covering it, the control, were stored in .a ventilated room at 2025 C. After ten days the dishes to which the dispersion had been added showed approximately a 50% reduction in evaporation compared to the control.

' Hence, this invention provides an improved process and composition for retarding the evaporation of water from bodies thereof.

Other features, advantages and specific embodiments of this invention will be readily apparent to those in the exercise of ordinary skill in the art after reading the foregoing disclosures. In this connection, while specific embodiments of this invention have been described in considerable detail, variations and modifications ofthese embodiments can be effected without departing from the spirit and scope of the invention substantially as disclosed and claimed.

We claim:

1. A process for retarding the evaporation of Water from a body thereof, which comprises forming on the surface of said body a thin film comprising normally solid, normally water insoluble, l-monoglyceride material consisting essentially of at least one l-monoglyceride of a saturated, straight chain, C1844 fatty acid, the concentration of said l-monoglyceride material being substantially greater than about by weight of said film.

2. A process according to claim 1 wherein said concentration of said l-monoglyceride material is in a range from about to about 100% by weight of said film.

3. A process according to claim 1 wherein said film is formed by adding to said body said l-monoglyceride material dispersed in water.

4. A process according to claim 1 wherein said l-monoglyceride material comprises the l-monoglyceride of behenic acid at a concentration of at least about by weight of said l-monoglyceride material.

5. A process according to claim 4 wherein said 1- monoglyceride material consists essentially of l-monoglycerides having the fatty acid moieties of distilled, substantially fully hydrogenated, rapeseed oil at the relative weight ratio of said moieties in said oil.

6. A process according to claim 1 wherein said film is formed by adding to said body said l monoglyceride material dissolved in a volatile, inert solvent therefor.

7. A process according to claim 6 wherein said solvent is n-hexane.

8. A process for retarding the evaporation of water from a body thereof, which comprises forming on the surface of said body a thin film consisting essentially of normally solid, normally water insoluble, C1444 primary alkanol material consisting essentially of at least one C1444 primary alkanol, the concentration of said alkanol material being substantially less than about 90% by weight of said film, and normally solid, normally water insoluble, l-monoglyceride material consisting essentially of at least one l-monoglyceride of a saturated, straight chain, C fatty acid, the concentration of said 1- monoglyceride material being substantially greater than about 10% by weight of said film.

9. A process according to claim 8 wherein the concentration of said alkanol material is in a range from about 10 to about 85% by weight of said film and the concentration of said l-monoglyceride material is in a range from about 15 to about 90% by weight of said film.

10. A process according to claim 9 wherein said alkanol material consists essentially of n-hexadecanol and n-octadecanol and wherein said l-monoglyceride material comprises the I-monoglyceride of behenic acid at a concentration of at least about 25% by weight of said l-monoglyceride material.

11. A process according to claim 9 wherein said film is formed by adding to said body said alkanol material and said l-monoglyceride material dissolved in a volatile, inert solvent therefor.

12. A process according to claim 9 wherein said alkanol 7 weight ratio of said moieties in said oil.

16. A process according to claim 9 wherein said film is formed by adding to said body said alkanol material and said l-monoglyceride material dispersed in water.

17. A process according to claim 16 wherein the aqueous dispersion of said alkanol material and said 1- monoglyceride material comprises a dispersing agent for said materials.

18. A process according to claim 17 wherein said dispersing agent is sodium stearate.

19. A composition for use in forming an evaporation suppressing film on the surface of a body of water, which consists essentially of a mixture of normally solid, normally water insoluble, C1444 primary alkanol material consisting essentially of at least one C1444 primary alkanol, the concentration of said alkanol material being substantially less than about 90% by weight of said mixture, and normally solid, normally water insoluble 1- monoglyceride material consisting essentially of at least one l-monoglyceride of a'saturated, straight chain, C1844 fatty acid, the concentration of said l-monoglyceride material being substantially greater than about 10% by weight of said mixture.

20. A composition according to claim-'19 wherein the concentration of said alkanol material is in a range from about 10 to about weight of said mixture and the concentration of said l-monoglyceride material is in a range from about 15 to about by weight of said mixture.

21. A composition according to claim 20 wherein said alkanol material consists essentially of n-hexadecanol and n-octadecanol and wherein said l-monoglyceride material comprises the l-monoglyceride of behenic acid at a concentration of at least about 25% by weight of said l-monoglyceride material.

22. A composition according to claim 20 wherein said mixture is dissolved in an inert solvent therefor.

23. A composition according to claim 20 wherein said alkanol material consists essentially of n-hexadecanol and n-octadecanol.

24. A composition according to claim 23 wherein the weight ratio of said n-hexadecanol to said n-octadecanol is substantially 3:7. 1

25. A composition according to claim 20 wherein said l-monoglyceride material comprises the l-mon'oglyceride of behenic acid at a' concentration of at least about 25 by weight of said l-monoglyceride material.

26. A composition according to claim 25 wherein said l-monoglyceride' material consists essentially of l-monoglycerides having a fatty acid moieties of distilled, substantially fully hydrogenated, rapeseed oil at the relative weight ratio of said moieties in said oil.

27. A composition according to claim'20 wherein said mixture is dissolved in water.

28. A composition according to claim 27 wherein the water concentration is in a range from about 50 to about 99% by weight of said dispersion-and the concentration of said mixture is in a range from about 1 to about 50% by weight of said dispersion.

29. A composition according to claim 27 wherein said composition comprises a dispersing agent for said mixture.

30. A composition according to claim 29 wherein the concentration of said dispersing agent is in a range from about 0.1 to about 2% by weight of said mixture.

31. A composition according to claim 30 wherein said dispersing agent is sodium stearate.

References Cited UNITED STATES PATENTS Millikan 21-6015 Cox 2160.5 Davis 21-60.5 Malkemus 2160.5 Egan 21-605 Suzuki et a1. 2160.5 Watanabe 2160.5 X Gabor et a1. 21-60.5

Mazur 21-605 10 FOREIGN PATENTS 898,431 6/1962 Great Britain.

OTHER REFERENCES MORRIS O. WOLK, Primary Examiner SIDNEY MARANTZ, Assistant Examiner U.S. Cl. X.R. 252--384 

